The use of in vitro metabolism of therapeutic agents to address the potential in vivo induction, inhibition, drug-drug interaction and individual variability issues is known (for a recent review, see Rodrigues, 1994, Biochem. Pharmacol. 48: 2147-2156). Central to these studies is the unambiguous identification of specific drug-metabolizing enzyme(s), particularly human cytochrome P450 isoform(s) responsible for the metabolism of drugs. This objective can be achieved by using selective cytochrome P450 inhibitors, antibodies, recombinant cytochrome P450s and correlation analysis (Rodrigues, 1994, Biochem. Pharmacol. 48: 2147-2156).
Polyclonal or monoclonal antibodies produced against purified cytochrome P450 or specific peptide sequences unique to individual cytochrome P450 isoforms have been used to study the regulation, structure and function of cytochrome P450s.
Leeder et al. (1996, Mol. Pharmacol. 49: 234-243) used epitope mapping studies to identify a minimum antibody binding sequence in CYP3A1 located in the K-helix of the protein.
Gelboin et al. (1995, Biochemical Pharmacology 50(11):1841-1850) disclose a monoclonal antibody which is inhibitory to human cytochrome P450 3A3/4/5.
Cribb et al. (1995, Drug Metabolism and Disposition 23(7): 671-675) disclose antipeptide antibodies against two overlapping synthetic peptides from human CYP2D6. Antipeptide antibodies against one of these synthetic peptides substantially inhibited recombinant human CYP2D6 activity.
Despite these advances, there remains a substantial need for specific and inhibitory antibodies to members of the human cytochrome P450 class of enzymes, especially to human CYP3A4. The present invention addresses and meets this need.